The invention relates to an actuating valve pneumatic cylinder comprising two pressure chambers separated from one another by a piston connected on a piston rod, which actuating valve comprises two 3/2 port directional control valves as relay valves connectable to a compressed air source and further comprises a valve system connected between these directional control valves and the pneumatic cylinder by which upon actuation of one of the two relay valves one of the pressure chambers can be loaded with compressed air and the other pressure chamber can be relieved of pressure via a venting throttle, respectively.
It is required in connection with such an actuating valve that after release of the respectively actuated relay valve, the pneumatic cylinder or its piston remains loaded with compressed air on both ends, that upon release of the previously actuated valve no further venting or pressure relief of both pressure chambers occurs, but that instead a positional locking of the pneumatic cylinder is effected, i.e., a bidirectional pneumatic cylinder should be moved by means of preferably manually actuated relay valves into its respective end positions and, upon cancellation of actuation, should be directly stoppable in its advancing movement.
This basic task is solved, for example, by a conventional cylinder control by means of a 5/3 port sliding valve that is controllable by two relay valves and has downstream thereof a venting throttle. The relay valves are usually 3/2 port sliding valves. In particular, when employing a 5/3 port sliding valve, this causes sealing problems between the individual valve channels as a result of the significant number of required lip seals.